Language laboratories have been extensively employed for many years. More recently, some of the techniques heretofore applied to language training have been extended to the teaching of music. To this end musical instruments are employed, which produce electrical signals but are, or can be, silent acoustically. It is desirable for one instructor to instruct a large number of pupils, say 24, for example. For convenience these may be divided into four groups, identified as A, B, C, D, respectively, each of which includes six students. It is then required that the instructor be enabled to listen to any one student, that the student be enabled to hear the playing of the instructor, or music deriving from one or more external sources, and that two-way voice communication between the student and the instructor be available at the option of the teacher. Further the students may play in ensemble, by group, or groups and also an intercommunication facility must exist in the sense that the students within a group must hear each other, and the teacher may hear the students of any group. In one system known to us, this has led to provision of 16 push buttons and five three-position switches, on a control panel available to the instructor, and to a two position switch at each student position, for solution of the communication problem. These switches must be manipulated in various combinations, to achieve various of the desired communication objectives, and flexibility of end result is achieved by complexity of manipulation, which may be unacceptable to the many music instructors who are electronically unsophisticated. The present invention concerns itself with the provision of a simpler control system, arranged physically to facilitate manipulation by virtue of compactness of a switch actuator array, and psychologically to facilitate understanding of the available functions of the switches and how these may be achieved. The present invention relates to simplification of electrical switching circuitry, in achieving a wide variety of possible interconnections.
It is a feature of the system that all intercommunication functions are under control of the teacher, in the sense that no student is called upon to operate controls to effect group relationships. Moreover no student can elect to call the teacher while the teacher is engaged with another student. Another feature is that the total number of switching elements is reduced in the present system in comparison with the number required in other systems of class music instructions known to us, which simplifies wiring and operation and reduces maintenance problems.